reload vs adds with clobbers

[Jim Wilson]

On Fri, 2003-06-06 at 05:17, DJ Delorie wrote:
> Unfortunately, all the const_int constraints are used up in that port.
> Does GCC play nice when you use an arbitrary constraint letter for
> const_ints?

No.  Reload needs to know that it is a constant constraint letter so
that it can call CONST_OK_FOR_LETTER_P.  There is EXTRA_CONSTRAINT that
might work.  You can use any letter that isn't used elsewhere in
EXTRA_CONSTRAINT.  You have to be careful not to use anything that has a
predefined meaning.  Generally capitol letters are safer than lower
case.

You can also use strings as constraint "letters" now, but I don't see
any port using this feature, so it seems risky to try to use it.

Jim